I may be. I don't know enough about what RTS/DTR is to know how or why it works.

I have an IC706mkiig, and it most definitely DOES have PTT over CAT. It works in FLRIG, Winlink, and JS8CALL without question. I get better performance on Winlink with PTT over CAT than I do with VOX through signalink. You DO still need to use the SignalinkUSB or Digirig Mobile to handle the audio either way though.

Rather than APRS you mean? I haven't gone beyond using APRSIS with JS8CALL so I can't help much, but I noticed that it only gets the pin on the correct grid, not the exact coordinates. Having a beacon with actual latitude and longitude with a visual map for all stations would be stellar.